  The Macdonald polynomials can be obtained by acting on the constant 1 with
creation operators. Three different expressions for these operators are
derived, one from the other, in a rather succint way. When the last of these
expressions is used, the formalism is seen to imply straightforwardly the
integrality of the (q,t)-Kostka coefficients, that is of the expansion
coefficients for the Macdonald functions in terms of Schur functions.
