Namespaces are the environment where all the functions of a package
live. The parent environments of namespaces are the imports
environments, which contain all the functions imported from other
packages.
ns_env(pkg = NULL)ns_imports_env(pkg = NULL)
ns_env_name(pkg = NULL)
The name of a package. If NULL
, the surrounding
namespace is returned, or an error is issued if not called within
a namespace. If a function, the enclosure of that function is
checked.