[Python] pyenv: no such command `virtualenv'

I'm following a tutorial on setting up torch on ubuntu 20.04 one line requires to setup pyenv which is like virtualenv for python so I can have multiple versions of python running. A bit unnecessary but it's a learning process and a good chance to learn of another new tool I might use another day.

So this command after successfully setting up pyenv fails

sam@sam:~/torch$ pyenv virtualenv 3.8.2 torch
pyenv: no such command `virtualenv'


so to cover my basics I already have virtualenv installed as shown here

sam@sam:~/torch$ virtualenv
usage: virtualenv [--version] [--with-traceback] [-v | -q] [--app-data APP_DATA] [--clear-app-data] [--discovery {builtin}] [-p py] [--creator {builtin,cpython3-posix,venv}] [--seeder {app-data,pip}] [--no-seed]
[--activators comma_sep_list] [--clear] [--system-site-packages] [--symlinks | --copies] [--download | --no-download] [--extra-search-dir d [d ...]] [--progress version] [--retrying version] [--urllib3 version]
[--pep517 version] [--colorama version] [--CacheControl version] [--certifi version] [--requests version] [--contextlib2 version] [--appdirs version] [--chardet version] [--pytoml version] [--html5lib version]
[--lockfile version] [--six version] [--webencodings version] [--pyparsing version] [--setuptools version] [--packaging version] [--wheel version] [--ipaddr version] [--idna version] [--pip version] [--distro version]
[--pkg_resources version] [--distlib version] [--msgpack version] [--no-progress] [--no-retrying] [--no-urllib3] [--no-pep517] [--no-colorama] [--no-CacheControl] [--no-certifi] [--no-requests] [--no-contextlib2]
[--no-appdirs] [--no-chardet] [--no-pytoml] [--no-html5lib] [--no-lockfile] [--no-six] [--no-webencodings] [--no-pyparsing] [--no-setuptools] [--no-packaging] [--no-wheel] [--no-ipaddr] [--no-idna] [--no-pip] [--no-distro]
[--no-pkg_resources] [--no-distlib] [--no-msgpack] [--symlink-app-data] [--prompt prompt] [-h]
dest
virtualenv: error: the following arguments are required: dest


and pyenv is installed as shown here

sam@sam:~/torch$ pyenv
pyenv 1.2.19-1-gece59ca8
Usage: pyenv <command> [<args>]

Some useful pyenv commands are:
commands List all available pyenv commands
exec Run an executable with the selected Python version
global Set or show the global Python version(s)
help Display help for a command
hooks List hook scripts for a given pyenv command
init Configure the shell environment for pyenv
install Install a Python version using python-build
local Set or show the local application-specific Python version(s)
prefix Display prefix for a Python version
rehash Rehash pyenv shims (run this after installing executables)
root Display the root directory where versions and shims are kept
shell Set or show the shell-specific Python version
shims List existing pyenv shims
uninstall Uninstall a specific Python version
--version Display the version of pyenv
version Show the current Python version(s) and its origin
version-file Detect the file that sets the current pyenv version
version-name Show the current Python version
version-origin Explain how the current Python version is set
versions List all Python versions available to pyenv
whence List all Python versions that contain the given executable
which Display the full path to an executable

See `pyenv help <command>' for information on a specific command.
For full documentation, see: https://github.com/pyenv/pyenv#readme

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