def stoichiometry_coefficient(compound, element):
stoichiometry = parse_compound(compound.strip()).count()<EOL>return stoichiometry[element]<EOL>
Determine the stoichiometry coefficient of an element in a chemical
compound.

:param compound: Formula of a chemical compound, e.g. 'SiO2'.
:param element:  Element, e.g. 'Si'.

:returns: Stoichiometry coefficient.