Can you explain the concept of currying in the context of programming?

Currying is a technique in functional programming where a function with multiple arguments is transformed into a sequence of functions, each taking a single argument.

In simpler terms, instead of calling a function with multiple parameters at once, you call a function that returns another function expecting the next parameter, and so on until all arguments are provided.

Example in Python:

def multiply(x):
    def multiply_by(y):
        return x * y
    return multiply_by

mul_by_3 = multiply(3)  # returns a function that multiplies by 3
result = mul_by_3(5)    # 15
print(result)

Currying is useful for creating partially applied functions and increasing code flexibility.