code: def stoichiometry_coefficient(compound, element):
      
  
      stoichiometry = parse_compound(compound.strip()).count()
  
      return stoichiometry[element]
docs: 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.