Map Reduce Python 3.x- TypeError: unsupported operand type(s) for |: 'str' and 'function'

Question

Taking a data science class and this is the textbook example, but I can't translate it into python 3.x.

---

import sys

def mapper():
    for line in sys.stdin:
        data = line.split(',')
        print (data[1] + ',' + data[2])
    
def reduce():
    high = 0

    for line in sys.stdin:
        data = line.split(',')
        close = float(data[1].rstrip())
    
    if (close > high):
        high = close
        date = data[0]
        
    print(date + ',' + str(high))

path = r'C:\Users\kingj\Downloads\stocks.csv'

mapper < path | reduce 

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I get this error:

----> 2 mapper < path | reduce

TypeError: unsupported operand type(s) for |: 'str' and 'function'