RegEx XV: Alternation

The vertical bar | is the equivalent to "or" in RegEx. The regular expression x|y matches either "x" or "y". Write the regular expression that will match all red flag and blue flag in a string. You must use | in your expression. Flags can come in any order.

Examples

txt1 = "red flag blue flag"
txt2 = "yellow flag red flag blue flag green flag"
txt3 = "pink flag red flag black flag blue flag green flag red flag"
pattern = "yourregularexpressionhere"

re.findall(pattern, txt1) ➞ ["red flag", "blue flag"]
re.findall(pattern, txt2) ➞ ["red flag", "blue flag"]
re.findall(pattern, txt3) ➞ ["red flag", "blue flag", "red flag"]

Notes

• You don't need to write a function, just the pattern.
• Do not remove import re from the code.
• You can find all the challenges of this series in my Basic RegEx collection.