'Returns the leading term of ``f``.
The Leading term signifies the term having
the highest power of the principal generator in the
expression f along with its coefficient.
Examples
>>> from sympy import Poly
>>> from sympy.abc import x, y
>>> Poly(4*x**2 + 2*x*y**2 + x*y + 3*y, x, y).LT()
(x**2*y**0, 4)'

def LT(f, order=None):

    (monom, coeff) = f.terms(order)[0]
    return (Monomial(monom, f.gens), coeff)
