code: def graph_edge(*, tail: str, head: str, attr: str) -> str:
      """Return DOT graph edge statement line."""
      return f"\t{tail} -- {head}{attr}\n"
  
imports: import contextlib
  import typing
  from .None import _tools
  from .None import base
  from .None import quoting
label_desc: Use image node_id 4 for calling a global function with example usage: graph_edge() and returns: str, tail, str, head, attr, str