Direnv function to aid with loading local virtualenv directories

.direnvrc

# Usage: layout_virtualenv <path>
# 
# Sets and loads a Python virtualenvironment from a local path
# Eg. `layout_virtualenv venv`
layout_virtualenv() {
  local venv_path=${1:-venv}
  log_status "Loading $venv_path"
  load_prefix ${venv_path}
  source ${venv_path}/bin/activate
}