`pgv_list()` |`table(package text, name text)`

`pgv_stats()` |`table(package text, used_memory bigint)`

* "array argument can not be NULL"

* "could not identify a hash function for type %s"

* "could not identify a matching function for type %s"

* "function returning record called in context that cannot accept type record"

* "name "%s" is too long"

* "new record structure differs from variable "%s" structure"

* "package name can not be NULL"

* "record argument can not be NULL"

* "requested value type differs from variable "%s" key type"

* "searching for elements in multidimensional arrays is not supported"

* "there is a record in the variable "%s" with same key"

* "unrecognized package "%s""

* "unrecognized variable "%s""

* "variable "%s" requires %s value"

* "variable name can not be NULL"

It is easy to use functions to work with scalar variables: