 The second simplification is that the lambda calculus only uses functions of a single input.An ordinary function that requires two inputs, for instance the formula_9 function, can be reworked into an equivalent function that accepts a single input, and as output returns "another" function, that in turn accepts a single input.For example, 
can be reworked into 
This method, known as currying, transforms a function that takes multiple arguments into a chain of functions each with a single argument.