docs: def trim(docstring):
      """
      Remove the tabs to spaces, and remove the extra spaces / tabs that are in
      front of the text in docstrings.
  
      Implementation taken from http://www.python.org/dev/peps/pep-0257/
      """
      if not docstring:
          return ''
      # Convert tabs to spaces (following the normal Python rules)
      # and split into a list of lines:
      lines = docstring.expandtabs().splitlines()
      # Determine minimum indentation (first line doesn't count):
      indent = sys.maxsize
      for line in lines[1:]:
          stripped = line.lstrip()
          if stripped:
              indent = min(indent, len(line) - len(stripped))
      # Remove indentation (first line is special):
      trimmed = [lines[0].strip()]
      if indent < sys.maxsize:
          for line in lines[1:]:
              trimmed.append(line[indent:].rstrip())
      # Strip off trailing and leading blank lines:
      while trimmed and not trimmed[-1]:
          trimmed.pop()
      while trimmed and not trimmed[0]:
          trimmed.pop(0)
      # Return a single string:
      res = '\n'.join(trimmed)
      if not PY3 and not isinstance(res, unicode):
          res = res.decode('utf8')
      return res