code: def one_run(runs, spec, ctx=None):
      """Returns runs[0] if len(runs) is 1 otherwise exits with an error."""
      if len(runs) == 1:
          return runs[0]
      if not runs:
          _no_matching_run_error(spec, ctx)
      _non_unique_run_id_error(runs, spec)
  
imports: import logging
  import os
  import typing
  from guild import cli
  from guild import click_util
  from guild import config
label_desc: Use image node_id 6 for calling a global function with example usage: one_run(runs, spec, ctx) and returns: runs