Human: count number of nan in numpy array. Assistant: 
Here is a Python program to count number of nan in numpy array

import numpy as np

def count_nan(arr):
    """Count number of nan in numpy array"""
    return np.sum(np.isnan(arr))

# Enter the array
arr = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])

# Calling the function
print((count_nan(arr)))

#Example Output
# 0

#Remember to inspect code for bugs.