IN - Find a value in list of values in Informatica

IN function in informatica searches for value in the list of values and returns TRUE (1) if available or FALSE(0) if no match is found. By default in function is case-sensitive.
IN( valueToSearch, value1, [value2, ..., valueN,] CaseFlag )

valueToSearchRequiredCan be a string, date, or numeric value. Input value you want to match against a comma-separated list of values. value Required Can be a string, date, or numeric value. Comma-separated list of values you want to search for. Values can be ports in a transformation. There is no maximum number of values you can list.
CaseFlagOptionalMust be an integer. Determines whether the arguments in this function are case sensitive. You can enter any valid transformation expression. When CaseFlag is a number other than 0, the function is case sensitive. When CaseFlag is a null value or 0, the function is not case sensitive.

Example : Check whether a person visited London or not