Merge the doc-sections of the parent's and child's attribute into a single docstring.

        Parameters
        ----------
        prnt_sctns: OrderedDict[str, Union[None,str]]
        child_sctns: OrderedDict[str, Union[None,str]]

        Returns
        -------
        str
            Output docstring of the merged docstrings.

def merge_all_sections(prnt_sctns, child_sctns, style):
    """ Merge the doc-sections of the parent's and child's attribute into a single docstring.

        Parameters
        ----------
        prnt_sctns: OrderedDict[str, Union[None,str]]
        child_sctns: OrderedDict[str, Union[None,str]]

        Returns
        -------
        str
            Output docstring of the merged docstrings."""
    doc = []

    prnt_only_raises = prnt_sctns["Raises"] and not (prnt_sctns["Returns"] or prnt_sctns["Yields"])
    if prnt_only_raises and (child_sctns["Returns"] or child_sctns["Yields"]):
        prnt_sctns["Raises"] = None

    for key in prnt_sctns:
        sect = merge_section(key, prnt_sctns[key], child_sctns[key], style)
        if sect is not None:
            doc.append(sect)
    return "\n\n".join(doc) if doc else None