Before a parameter can be added to a request, it often needs to be cleaned. This function returns the appropriate function for a parameter. Parameters can be supplied with their name used in the build() functions ("argument") or in the URL

get_cleaning_function(parameter, format = c("argument", "url"))

## Arguments

parameter character; name of the parameter. Either the parameter as it's passed to the build() functions or the name of the parameter in the URL depending on the value of format character; what format is parameter in? One of "argument" (default) or "url"

## Value

character; name of the cleaning function. If there is no associated cleaning function, then NULL