def METHOD_NAME(connection_file, profile=None):
    """Return the absolute path for a connection file
    - If nothing specified, return current Kernel's connection file
    - If profile specified, show deprecation warning about finding connection files in profiles
    - Otherwise, call jupyter_client.find_connection_file
    """
    if connection_file is None:
        # get connection file from current kernel
        return get_connection_file()
    else:
        # connection file specified, allow shortnames:
        if profile is not None:
            warnings.warn(
                "Finding connection file by profile is deprecated.",
                DeprecationWarning, stacklevel=3,
            )
            return find_connection_file(connection_file, profile=profile)
        else:
            return jupyter_client.find_connection_file(connection_file)