make.keys: creates/coerces objects to proper hash keys
Description
Given an vector of any type, make.keys tries to coerce it into a
character vector that can be used as a hash key. This is used internally
by the hash package and should not be normally needed.
Usage
make.keys(key)
Value
A character vector of valid keys
Arguments
key
An object that represents the key(s) to be coerced to a valid hash keys.
Author
Christopher Brown
Details
This function is used internally by the hash class to
ensure that the keys are valid. There should be no need to use this
externally and is only documented for completeness.