function cwrap(ident, returnType, argTypes, opts) {
  argTypes = argTypes || [];
  // When the function takes numbers and returns a number, we can just return
  // the original function
  var numericArgs = argTypes.every(function(type){ return type === 'number'});
  var numericRet = returnType !== 'string';
  if (numericRet && numericArgs && !opts) {
    return getCFunc(ident);
  }
  return function() {
    return ccall(ident, returnType, argTypes, arguments, opts);
  }
}
@param {string=} returnType
    @param {Array=} argTypes
    @param {Object=} opts