Strip Split Join.

Third class. Real text often arrives with extra spaces or as pieces to combine.

strip() removes leading and trailing whitespace. It does not touch spaces in the middle.

split(sep) breaks a string into a list of parts on a separator. For example "a,b,c".split(",") → ["a", "b", "c"].

join is a method on the separator: "-".join(parts) glues list items with "-" between them. The order is separator.join(list), not the other way around.

Mini example:

raw = "  a,b  "
clean = raw.strip()
parts = clean.split(",")
print("-".join(parts))

Common mistake: parts.join("-") — that is not the Python string style; or expecting strip() to remove spaces in the middle.