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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def mason_morrow(target, throat_perimeter='throat.perimeter', throat_area='throat.area'):
 r""" Mason and Morrow relate the capillary pressure to the shaped factor in a similar way to Mortensen but for triangles. References Mason, G. and Morrow, N.R.. Capillary behavior of a perfectly wetting liquid in irregular triangular tubes. Journal of Colloid and Interface Science, 141(1), pp.262-274 (1991). """

    # Only apply to throats with an area
    ts = target.throats()[target[throat_area] <= 0]
    P = target[throat_perimeter]
    A = target[throat_area]
    value = A/(P**2)
    value[ts] = 1/(4*_sp.pi)
    return value