Writing an UDF for withColumn in PySpark

pyspark-udf.py

from pyspark.sql.types import StringType
from pyspark.sql.functions import udf

maturity_udf = udf(lambda age: "adult" if age >=18 else "child", StringType())

df = spark.createDataFrame([{'name': 'Alice', 'age': 1}])
df.withColumn("maturity", maturity_udf(df.age))

df.show()

TypeError: a bytes-like object is required, not 'NoneType'

I am getting this error while trying 'mrandrewandrade' input.
How can I resolve this error?

Thanks.

It was nice to come across my teacher's code even after graduation. Thank you!

I encountered this problem too. Have you solved it? Thank you!