Merge merges raw variable values b into a.

ParseInput parses a manually inputed variable to a richer value.

Flag a flag.Value implementation for parsing user variables from the command-line in the format of '-var key=value', where value is a type intended for use as a Terraform variable.

FlagAny is a flag.Value for parsing user variables in the format of 'key=value' OR a file path.

FlagFile is a flag.Value implementation for parsing user variables from the command line in the form of files.