diff --git a/apply_MBEDTLS_PRIVATE.py b/apply_MBEDTLS_PRIVATE.py
index 4160287..4d87384 100644
--- a/apply_MBEDTLS_PRIVATE.py
+++ b/apply_MBEDTLS_PRIVATE.py
@@ -6,32 +6,41 @@
 import xml.etree.ElementTree as ET
 
 
+# Create dictionary with following structre
+# files_to_visit = {
+#     "filepath1" : { "variable_name1": (1, 2, 40, 61),  # line numbers
+#                     "variable_name2": (60, 64),
+#                   },
+#     "filepath2" : { "variable_name1": (1, 2, 40, 61),  # line numbers
+#                     "variable_name2": (60, 64),
+#                   }, ...
+# }
 files_to_visit = {}
 
+# find xml models for structs parsed by doxygen
 struct_files = glob.glob("apidoc/xml/structmbedtls*.xml") + glob.glob("apidoc/xml/structpsa*.xml")
 
 for struct_file in struct_files:
+  # get all variables from currently processed struct
   struct_file_tree = ET.parse(struct_file)
   all_struct_members_definitions = struct_file_tree.getroot().findall(".//memberdef[@kind='variable']")
 
-  # Create dictionary with following structre
-  # "filepath" : { "variable_name1": (1, 2, 40, 61),  # line numbers
-  #                "variable_name2": (60, 64),
-  #              }
   for struct_member_def in all_struct_members_definitions:
-    # find file path for this variable
+    # get unique id by which this variable is referenced
     member_id = struct_member_def.attrib["id"]
+    # find file path for this variable's definition
     location = struct_member_def.find("location")
     file_path = location.attrib["file"]
+    # get variable name
     variable_name = struct_member_def.find("name").text
-    # if path not yet in dictionary, create empty record to initialize
+    # if file path is not yet in dictionary, create empty sub-dictionary to initialize
     if file_path not in files_to_visit:
       files_to_visit[file_path] = {}
     # if variable is not yet in this file's dictionary, create empty set to initialize
     if variable_name not in files_to_visit[file_path]:
       files_to_visit[file_path][variable_name] = set()
 
-    # add variable definition
+    # add variable's definition line number
     files_to_visit[file_path][variable_name].add(int(location.attrib["line"]))
 
     # check where the variable was referenced
@@ -39,13 +48,13 @@
     for reference in references:
       refid = reference.attrib["refid"]
       # assuming that compound name is related to header's xml file
-      header_file = "apidoc/xml/" + reference.attrib["compoundref"] + ".xml"
-      header_file_tree = ET.parse(header_file)
+      header_file_xml = "apidoc/xml/" + reference.attrib["compoundref"] + ".xml"
+      header_file_tree = ET.parse(header_file_xml)
       # check if this reference is created by static inline function
       static_inline_function_definition = header_file_tree.getroot().find(f".//memberdef[@id='{refid}'][@kind='function'][@static='yes'][@inline='yes']")
       if static_inline_function_definition:
         static_inline_function_file_path = static_inline_function_definition.find("location").attrib["file"]
-        # if path not yet in dictionary, create empty record to initialize.
+        # if file path not yet in dictionary, create empty sub-dictionary to initialize.
         # This could happen if reference is inside header file which was not yet processed in search for variable definitions
         if static_inline_function_file_path not in files_to_visit:
           files_to_visit[static_inline_function_file_path] = {}
@@ -55,26 +64,30 @@
         # function block scope
         function_lines_from = int(reference.attrib["startline"])
         function_lines_to = int(reference.attrib["endline"])
-        # find codelines referencing struct's variable
+        # find codelines referencing currently processed variable. This is using the code listing inside header's xml model.
         codelines_xml = header_file_tree.getroot().findall(f".//ref[@refid='{member_id}']/../..")
         # filter by function's scope
         codelines = [int(line.attrib["lineno"]) for line in codelines_xml if int(line.attrib["lineno"]) >= function_lines_from and int(line.attrib["lineno"]) <= function_lines_to]
-        # add variable reference
+        # add lines referencing currently processed variable
         files_to_visit[static_inline_function_file_path][variable_name].update(codelines)
 
 pp = pprint.PrettyPrinter(indent=4)
 pp.pprint(files_to_visit)
 
 for file_path, variables in files_to_visit.items():
+  # FileInput redirects stdout to to 'file', so every print in this block will be put inside 'file'
   with fileinput.FileInput(file_path, inplace=True) as file:
     output_line_number = 1
+    # compile regex matching the header's include guard.
     re_include_guard = re.compile(r"^#define.*{name}$".format(name=os.path.basename(file_path).replace('.','_').upper()))
     for line in file:
       insert_allow_private_include = False
       if re_include_guard.match(line):
         insert_allow_private_include = True
+      # every line in file is checked against variables and lines in which they occur
       for variable, var_lines in variables.items():
         for var_line in var_lines:
+          # wrap variable with MBEDTLS_PRIVATE(...) macro
           if output_line_number == var_line:
             line = re.sub(r"(^.*?\W+)({var})(\W+.*$)".format(var=variable), r"\1MBEDTLS_PRIVATE(\2)\3", line)
       output_line_number += 1