input: Write a function to calculate the distance between two points using their coordinates. The function should take four parameters: x1, y1 for the first point, and x2, y2 for the second point. The function should return the calculated distance.
  assert distance_between_points(2, 7, 4, 9) == math.sqrt(8)
  assert distance_between_points(0, 0, 3, 4) == 5.0
  assert distance_between_points(-1, -1, 2, 3) == 5.0
  assert distance_between_points(1, 1, 2, 2) == math.sqrt(2)
  assert distance_between_points(0, 0, 0, 0) == 0.0
output: import math
  
  def distance_between_points(x1, y1, x2, y2):
      return math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)