input: Write a python function to identify a triangle using 3 provided side lengths.
  assert is_valid_triangle(3, 4, 5) == True
  assert is_valid_triangle(1, 1, 2) == False
  assert is_valid_triangle(6, 8, 10) == True
  assert is_valid_triangle(1, 2, 3) == False
  assert is_valid_triangle(7, 10, 5) == True
output: def is_valid_triangle(a, b, c):
      return a + b > c and a + c > b and b + c > a