# Returns set with one feature pact if specified
    >>> body = 'gitlab: mygitlaburl.com\\r\\nfeature-pacts: zh-feature-a'
    >>> _pluck_feature_pacts(body) == frozenset({'zh-feature-a'})
    True

    # Returns set with multiple feature pacts if specified
    >>> body = 'gitlab: mygitlaburl.com\\r\\nfeature-pacts: zh-feature-a eh-feature-b\\r\\nurgent!'
    >>> _pluck_feature_pacts(body) == frozenset({'zh-feature-a', 'eh-feature-b'})
    True

    # Returns empty set if no feature-pacts line
    >>> body = 'gitlab: mygitlaburl.com\\r\\n\\r\\nJust adding some documentation'
    >>> _pluck_feature_pacts(body)
    frozenset()

    # Returns empty set if feature-pacts line with no tags
    >>> body = 'gitlab: mygitlaburl.com\\r\\n\\r\\nfeature-pacts:\\r\\nJust adding some docs'
    >>> _pluck_feature_pacts(body)
    frozenset()

    # Raises a GithubPrError if multiple feature-pact lines found
    >>> body = 'feature-pacts: zh-feature-a\\r\\nfeature-pacts: eh-feature-b'
    >>> _pluck_feature_pacts(body)
    Traceback (most recent call last):
        ...
    faaspact_verifier.delivery.github_prs.GithubPrError: ...

def _pluck_feature_pacts(pr_body: str) -> FrozenSet[str]:
    """
    # Returns set with one feature pact if specified
    >>> body = 'gitlab: mygitlaburl.com\\r\\nfeature-pacts: zh-feature-a'
    >>> _pluck_feature_pacts(body) == frozenset({'zh-feature-a'})
    True

    # Returns set with multiple feature pacts if specified
    >>> body = 'gitlab: mygitlaburl.com\\r\\nfeature-pacts: zh-feature-a eh-feature-b\\r\\nurgent!'
    >>> _pluck_feature_pacts(body) == frozenset({'zh-feature-a', 'eh-feature-b'})
    True

    # Returns empty set if no feature-pacts line
    >>> body = 'gitlab: mygitlaburl.com\\r\\n\\r\\nJust adding some documentation'
    >>> _pluck_feature_pacts(body)
    frozenset()

    # Returns empty set if feature-pacts line with no tags
    >>> body = 'gitlab: mygitlaburl.com\\r\\n\\r\\nfeature-pacts:\\r\\nJust adding some docs'
    >>> _pluck_feature_pacts(body)
    frozenset()

    # Raises a GithubPrError if multiple feature-pact lines found
    >>> body = 'feature-pacts: zh-feature-a\\r\\nfeature-pacts: eh-feature-b'
    >>> _pluck_feature_pacts(body)
    Traceback (most recent call last):
        ...
    faaspact_verifier.delivery.github_prs.GithubPrError: ...
    """
    feature_pact_lines = [line for line in pr_body.split('\r\n')
                          if line.startswith('feature-pacts:')]
    if not feature_pact_lines:
        return frozenset()
    if len(feature_pact_lines) > 1:
        raise GithubPrError(f'There should only be one feature-pacts line. "{feature_pact_lines}"')
    return frozenset(feature_pact_lines[0].split()[1:])