human
program calculating angle from two points.
assistant
Here is a Python function for calculating angle from two points

import numpy as np

def angle(x1, y1, x2, y2):
    """
    Calculate angle between two points.
    """
    return np.arctan2(y2 - y1, x2 - x1)

# Enter the x1, y1, x2, y2
x1 = 1
y1 = 1
x2 = 2
y2 = 2

# Calling the function
print((angle(x1, y1, x2, y2)))

#Example Output
# 0.7853981633974483

#Remember to inspect code for bugs.