function pmf( x, p ) {
	return addon( x, p );
}
Evaluates the probability mass function (PMF) for a Bernoulli distribution with success probability `p` at a value `x`.

@private
@param {number} x - input value
@param {Probability} p - success probability
@returns {Probability} evaluated PMF

@example
var y = pmf( 1.0, 0.3 );
// returns 0.3

@example
var y = pmf( 0.0, 0.3 );
// returns 0.7

@example
var y = pmf( -1.0, 0.5 );
// returns 0.0

@example
var y = pmf( NaN, 0.0 );
// returns NaN

@example
var y = pmf( 0.0, NaN );
// returns NaN

@example
var y = pmf( 0.0, -1.0 );
// returns NaN

@example
var y = pmf( 0.0, 1.5 );
// returns NaN