<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def issue(ctx, accountable, issue_key):
 """ List metadata for a given issue key. """

    accountable.issue_key = issue_key
    if not ctx.invoked_subcommand:
        issue = accountable.issue_meta()
        headers = issue.keys()
        rows = [headers, [v for k, v in issue.items()]]
        print_table(SingleTable(rows))