def is_git(repository):

    if hasattr(repository, 'alias'):

        _type = repository.alias

    elif hasattr(repository, 'repo_type'):

        _type = repository.repo_type

    else:

        _type = repository

    return _type == 'git'

def is_hg(repository):

    if hasattr(repository, 'alias'):

        _type = repository.alias

    elif hasattr(repository, 'repo_type'):

        _type = repository.repo_type

    else:

        _type = repository

    return _type == 'hg'

def user_or_none(author):

    email = author_email(author)

        user = User.get_by_email(email, case_insensitive=True, cache=True)

        if user is not None:

            return user

    user = User.get_by_username(author_name(author), case_insensitive=True, cache=True)

    if user is not None:

        return user

    return None

def email_or_none(author):

    if not author:

        return None

    user = user_or_none(author)

    if user is not None:

        return user.email # always use main email address - not necessarily the one used to find user

    # extract email from the commit string

    email = author_email(author)

    if email:

        return email

    # No valid email, not a valid user in the system, none!

    return None