def common_doc(doc_dict):
    """Decorator: replaces commond fields in a function docstring

    Parameters
    -----------
    doc_dict : dict
        Dictionary of parameters that will be used to format a doctring. e.g. func.__doc__.format(**doc_dict)
    """

    def _decorator(func):
        if func.__doc__ is None:
            return func

        func.__doc__ = func.__doc__.format(**doc_dict)
        return func

    return _decorator