'Returns True if indices are either both above or below fermi.
Examples
>>> from sympy.functions.special.tensor_functions import KroneckerDelta
>>> from sympy import Symbol
>>> a = Symbol(\'a\', above_fermi=True)
>>> i = Symbol(\'i\', below_fermi=True)
>>> p = Symbol(\'p\')
>>> q = Symbol(\'q\')
>>> KroneckerDelta(p, q).indices_contain_equal_information
True
>>> KroneckerDelta(p, q+1).indices_contain_equal_information
True
>>> KroneckerDelta(i, p).indices_contain_equal_information
False'

@property
def indices_contain_equal_information(self):

    if (self.args[0].assumptions0.get('below_fermi') and self.args[1].assumptions0.get('below_fermi')):
        return True
    if (self.args[0].assumptions0.get('above_fermi') and self.args[1].assumptions0.get('above_fermi')):
        return True
    return (self.is_below_fermi and self.is_above_fermi)
