Human: angle between two vector. Assistant: 
Here is a Python function to angle between two vectors

import numpy as np

def angle(v1, v2):
    """Returns the angle between two vectors."""
    return np.arccos(np.dot(v1, v2) / (np.linalg.norm(v1) * np.linalg.norm(v2)))

# Enter the vector
vector1 = np.array([1, 2, 3])

# Enter the vector
vector2 = np.array([4, 5, 6])

# Calling the function
print((angle(vector1, vector2)))

#Example Output
# 0.2257261285527342

#Remember to inspect code for bugs.