python rpn with support for unary and ternary operator (+ ready for more )

rpn.py

import inspect

ops = {
    "+": lambda a, b: a + b,
    "-": lambda a, b: a - b,
    "x": lambda a, b: a * b,
    "/": lambda a, b: a / b,
    "sqrt": lambda a: a ** 0.5,
    "ternary_operator": lambda a, b, c: a + b + c + 1,
}
ops = {
    token: (func, len(inspect.getfullargspec(func).args)) 
    for token, func in ops.items()
}
# first element of tuple is the function to execute
# second is the number of operators it consumes

def rpn(entry):
    def pop_elements(stack, x):
        return [stack.pop() for i in range(x)][::-1]

    stack = []
    try:
        for token in entry.split():
            # print(stack)
            if token in ops:
                nums = pop_elements(stack, ops[token][1])
                z = ops[token][0](*nums)
                stack.append(z)
            else:
                # should be an number
                stack.append(float(token))
        assert len(stack) == 1
    except (IndexError, AssertionError):
        print("Malformed operation")
    except ValueError:
        print("this only supports numbers")
    else:
        return stack[0]

    
if __name__ == '__main__':
    rpn("1.44 2 / 3.2 x 5 - sqrt")