<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def gamma_humic_acid_to_coag(ConcAl, ConcNatOrgMat, NatOrgMat, coag):
 """Return the fraction of the coagulant that is coated with humic acid. :param ConcAl: Concentration of alumninum in solution :type ConcAl: float :param ConcNatOrgMat: Concentration of natural organic matter in solution :type ConcNatOrgMat: float :param NatOrgMat: type of natural organic matter, e.g. floc_model.HumicAcid :type NatOrgMat: floc_model.Material :param coag: Type of coagulant in solution, e.g. floc_model.PACl :type coag: floc_model.Material :return: fraction of the coagulant that is coated with humic acid :rtype: float """

    return min(((ConcNatOrgMat / conc_precipitate(ConcAl, coag).magnitude)
                * (coag.Density / NatOrgMat.Density)
                * (coag.Diameter / (4 * NatOrgMat.Diameter))
                ),
               1)