docs: def find_file_regex(root_dir,re_expression,return_abs_path = True,search_sub_directories = True):
      '''
          Finds all the files with the specified root directory with the name matching the regex expression.
          Args    :
              root_dir                : The root directory.
              re_expression           : The regex expression.
              return_abs_path         : If set to true, returns the absolute path of the files, else returns the name of the files.
              search_sub_directories  : If set to true, searches sub directories recursivly.
      '''
  
      compiled        = re.compile(re_expression)
      result          = []
      for dirpath, dirnames, files in os.walk(root_dir) :
          #Select files matching the expression
          for file in files :
              if compiled.match(file):
                  result.append(os.path.join(dirpath,file) if return_abs_path else file )
  
          #Break if no sub-directories
          if not search_sub_directories :
              break
      return result