I'm getting an "ERROR: Invalid Python Code. The code you created is not a valid Python code, with error: invalid syntax (Uppercase Converter, line 1), here is my code:

```python
import re
def getSentenceCase(source: str):
    output = ""
    isFirstWord = True

    for c in source:
        if isFirstWord and not c.isspace():
            c = c.upper()
            isFirstWord = False
        elif not isFirstWord and c in ".!?":
            isFirstWord = True
        else:
            c = c.lower()

        output = output + c

    return output

var1 = """strings are one of the most commonly used
data types in almost every programming language. it
allows you to store custom data, your options, and more.
IN FACT, THIS ANNOUNCEMENT IS A SERIES OF STRINGS!"""

print(getSentenceCase(var1))
# Expected output:
# Strings are one of the most commonly used
# data types in almost every programming language. It
# allows you to store custom data, your options, and more.
# In fact, this announcement is a series of strings!
 Write your response using less than 100 words.
user