def get_isotopic_ratio(self, compound='<STR_LIT>', element='<STR_LIT>'):
_stack = self.stack<EOL>compound = str(compound)<EOL>if compound == '<STR_LIT>':<EOL><INDENT>_list_compounds = _stack.keys()<EOL>list_all_dict = {}<EOL>for _compound in _list_compounds:<EOL><INDENT>_compound = str(_compound)<EOL>_list_element = _stack[_compound]['<STR_LIT>']<EOL>list_all_dict[_compound] = {}<EOL>for _element in _list_element:<EOL><INDENT>list_all_dict[_compound][_element] = self.get_isotopic_ratio(<EOL>compound=_compound,<EOL>element=_element)<EOL><DEDENT><DEDENT>return list_all_dict<EOL><DEDENT>list_compounds = _stack.keys()<EOL>if compound not in list_compounds:<EOL><INDENT>list_compounds_joined = '<STR_LIT:U+002CU+0020>'.join(list_compounds)<EOL>raise ValueError("<STR_LIT>".format(compound, list_compounds_joined))<EOL><DEDENT>if element == '<STR_LIT>':<EOL><INDENT>element = compound<EOL><DEDENT>list_element = _stack[compound].keys()<EOL>if element not in list_element:<EOL><INDENT>list_element_joined = '<STR_LIT:U+002CU+0020>'.join(list_element)<EOL>raise ValueError("<STR_LIT>".format(element, list_element_joined))<EOL><DEDENT>list_istopes = _stack[compound][element]['<STR_LIT>']['<STR_LIT:list>']<EOL>list_ratio = _stack[compound][element]['<STR_LIT>']['<STR_LIT>']<EOL>iso_ratio = zip(list_istopes, list_ratio)<EOL>_stoichiometric_ratio = {}<EOL>for _iso, _ratio in iso_ratio:<EOL><INDENT>_stoichiometric_ratio[_iso] = _ratio<EOL><DEDENT>return _stoichiometric_ratio<EOL>
returns the list of isotopes for the element of the compound defined with their stoichiometric values

        Parameters:
        ===========
        compound: string (default is empty). If empty, all the stoichiometric will be displayed
        element: string (default is same as compound).

        Raises:
        =======
        ValueError if element is not defined in the stack