I'm very new to python and I have one question.
In this code,

```
def abc(a,b,c):
        s = x+y+z
        q=(x+y+z)/2
        a = (q*(q-x)*(q-y)*(q-z))**0.5
        return (s,a)

print("Enter sides of a triangle")
x = float(input("a: "))
y = float(input("b: "))
z = float(input("c: "))
if x+y>z and x+z>y and y+z>x :
        print("Triangle is valid")
        tuple = abc(x,y,z)
else:
        print("Triangle is invalid")
print("PERIMETER and AREA OF TRIANGLE", tuple)

```

In the function definition of abc, I passed the variable names as a, b,c but I used them as x, y, z only and the output is also correct. Why this isn't showing any error? Is this correct?