code: def load_file_to_base64_str(f_path):
      
      path = abs_path(f_path)
      with io.open(path, 'rb') as f:
          f_bytes = f.read()
          base64_str = base64.b64encode(f_bytes).decode("utf-8")
          return base64_str
docs: Loads the content of a file into a base64 string.
  
      Args:
          f_path: full path to the file including the file name.
  
      Returns:
          A base64 string representing the content of the file in utf-8 encoding.