function baseArity(func, n) {
  return n == 2
    ? function(a, b) { return func.apply(undefined, arguments); }
    : function(a) { return func.apply(undefined, arguments); };
}
Creates a function, with an arity of `n`, that invokes `func` with the
arguments it receives.

@private
@param {Function} func The function to wrap.
@param {number} n The arity of the new function.
@returns {Function} Returns the new function.