 The mock modular form "h" is holomorphic but not quite modular, while "h" + "g"* is modular but not quite holomorphic.The space of mock modular forms of weight "k" contains the space of nearly modular forms ("modular forms that may be meromorphic at cusps") of weight "k" as a subspace.The quotient is (antilinearly) isomorphic to the space of holomorphic modular forms of weight 2 − "k".