Human: index of largest value of array. Assistant: 
Here is a Python program to index the largest value of arrays

import numpy as np

def largest_index(array):
    """Return index of largest value of array."""
    return np.argmax(array)

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

# Calling the function
index = largest_index(array)

# Printing the result
print(index)

#Example Output
# 9

#Remember to inspect code for bugs.