def getSpeciesValue(species):
    """
    Return the initial amount of a species.
    If species.isSetInitialAmount() == True, return the initial amount.
    Otherwise, return the initial concentration.

    ***** args *****
    
    species:    a libsbml.Species object
    
    """

    if species.isSetInitialAmount():
        return species.getInitialAmount()
    else:
        return species.getInitialConcentration()