Type of error in phyton 'str' object is not callable

import pandas as pd
ds1 = pd.Series(np.random.randn(5)) #serie 1
ds2 = pd.Series(np.random.randn(5)) #serie2
print("Series1:")
print(ds1)
print("Series2:")
print(ds2)
print("Compare the elements of the said Series:")
print("Equals:")
print(ds1 == ds2)
print("Greater than:")
print(ds1 > ds2)
print("Less than:")
print(ds1 < ds2)

Hello! I comment, I must compare elements (max, min and equal) two series generated randomly in phyton, the error that throws me do not understand: TypeError: 'str' object is not callable ... What am I doing wrong?