code: def _get_indent(marker, s, tab_width=8):
      
      # Figure out how much the marker is indented.
      INDENT_CHARS = tuple(' \t')
      start = s.index(marker)
      i = start
      while i > 0:
          if s[i - 1] not in INDENT_CHARS:
              break
          i -= 1
      indent = s[i:start]
      indent_width = 0
      for ch in indent:
          if ch == ' ':
              indent_width += 1
          elif ch == '\t':
              indent_width += tab_width - (indent_width % tab_width)
      return indent, indent_width
docs: _get_indent(marker, s, tab_width=8) ->
          (<indentation-of-'marker'>, <indentation-width>)