notebook - pyspark expression

Question

Hello,

This pyspark code as you see below, converts the Contact field values to upper case.

from pyspark.sql.functions import expr

vExpression = 'upper'
vCDF = (
vCDF
.withColumn("Contact",upper('Contact'))
)

display(vvCDF.limit(10))

---

Question:
How is it possible to use the variable vExpression to upper case the Contact field values so that I do not have to type upper in the .withColumn section?

Thank you