Write a function called blur that blurs the input image

Sure, here is a simple function in Python using OpenCV library to blur an image:

import cv2

def blur(image_path):
    # Load an image using OpenCV
    img = cv2.imread(image_path)

    # Apply a Gaussian blur to the image
    blurred_img = cv2.GaussianBlur(img, (5, 5), 0)

    # Save the result
    cv2.imwrite('blurred_image.jpg', blurred_img)

    return blurred_img

This function takes an image path as an input, reads the image using OpenCV's imread function, applies a Gaussian blur using the GaussianBlur function, and then saves the result. The (5, 5) in the GaussianBlur function is the kernel size (the size of the window that is convolved with the image), and the 0 is the standard deviation in the X and Y directions; a value of 0 means that the standard deviations are computed from the kernel size.

You can call this function with the path to the image you want to blur as follows:

blurred_image = blur('path_to_your_image.jpg')

Please make sure to replace 'path_to_your_image.jpg' with the actual path to your image.