[Python] Numpy Bug in computing business days?

I am trying to compute business days using Numpy.

I how ever found an inconsistency.

import numpy as np

# Count from 1st Jan 2023 to 31st Jan 2023
print("Jan: {0}".format(np.busday_count('2023-01-01', '2023-01-31')))

# Returns 21 days
# To get actual business days do 21 + 1 = 22, since start day is not counted


For December;

import numpy as np

# Count from 1st Dec 2023 to 31st Dec 2023
print("Dec: {0}".format(np.busday_count('2023-12-01', '2023-12-31')))

# Returns 21 days
# To get actual business days, use 21, which is the actual number of business days in December.
# So adding 21 + 1 would give an incorrect number of 22 business days.


Is this a bug? or am I simply using Numpy wrong?

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