def reaction_elements(reaction):
c_elements = [coeff * met.elements.get('<STR_LIT:C>', <NUM_LIT:0>)<EOL>for met, coeff in iteritems(reaction.metabolites)]<EOL>return [elem for elem in c_elements if elem != <NUM_LIT:0>]<EOL>
Split metabolites into the atoms times their stoichiometric coefficients.

Parameters
----------
reaction : Reaction
    The metabolic reaction whose components are desired.

Returns
-------
list
    Each of the reaction's metabolites' desired carbon elements (if any)
    times that metabolite's stoichiometric coefficient.