Create empty conda environment

I can create a new conda environment, with program biopython with this:

    conda create --name snowflakes biopython

What if I do not want to install any program? It seems I can not do that:

    » conda create --name tryout
    Error: too few arguments, must supply command line package specs or --file

    You can specify one or more default packages to install when creating
    an environment.  Doing so allows you to call conda create without
    explicitly providing any package names.

    To set the provided packages, call conda config like this:

        conda config --add create_default_packages PACKAGE_NAME

You can give a package name of just "python" to get a base, empty install.

    conda create --name myenv python
    conda create --name myenv python=3.4