Update digital_differential_analyzer_line.py

Author: nababuddin

graphics/digital_differential_analyzer_line.py

@@ -1,25 +1,40 @@
 import matplotlib.pyplot as plt
 
-
 def digital_differential_analyzer_line(
     x1: int, y1: int, x2: int, y2: int
 ) -> list[tuple[int, int]]:
+    """
+    Draws a line between two points using the Digital Differential Analyzer (DDA) algorithm.
+    
+    Args:
+    - x1, y1: Coordinates of the starting point.
+    - x2, y2: Coordinates of the ending point.
+
+    Returns:
+    - List of coordinate points that form the line.
+
+    >>> digital_differential_analyzer_line(1, 1, 4, 4)
+    [(2, 2), (3, 3), (4, 4)]
+    """
+    
     dx = x2 - x1
     dy = y2 - y1
     steps = max(abs(dx), abs(dy))
     x_increment = dx / float(steps)
     y_increment = dy / float(steps)
     coordinates = []
-    x = x1
-    y = y1
+    x: float = x1
+    y: float = y1
     for _ in range(steps):
         x += x_increment
         y += y_increment
         coordinates.append((int(round(x)), int(round(y))))
     return coordinates
 
-
 if __name__ == "__main__":
+    import doctest
+    doctest.testmod()
+    
     x1 = int(input("Enter the x-coordinate of the starting point: "))
     y1 = int(input("Enter the y-coordinate of the starting point: "))
     x2 = int(input("Enter the x-coordinate of the ending point: "))