virtualenvwrapper='virtualenvwrapper.sh'
  
  if (( $+commands[$virtualenvwrapper] )); then

    function {
      setopt local_options
      unsetopt equals
      source ${${virtualenvwrapper}:c}
    }

  elif [[ -f "/etc/bash_completion.d/virtualenvwrapper" ]]; then

    function {
      setopt local_options
      unsetopt equals
      virtualenvwrapper="/etc/bash_completion.d/virtualenvwrapper"
      source "/etc/bash_completion.d/virtualenvwrapper"
    }

  else

    print "[oh-my-zsh] virtualenvwrapper plugin: Cannot find ${virtualenvwrapper}.
  "\

          "Please install with \`pip install virtualenvwrapper\`" >&2
    return
  fi
  if ! type workon &>/dev/null; then

    print "[oh-my-zsh] virtualenvwrapper plugin: shell function 'workon' not defined.
  "\

          "Please check ${virtualenvwrapper}" >&2
    return
  fi
  
  if [[ "$WORKON_HOME" == "" ]]; then

    print "[oh-my-zsh] \$WORKON_HOME is not defined so plugin virtualenvwrapper will not work" >&2

    return
  fi
  
  if [[ ! $DISABLE_VENV_CD -eq 1 ]]; then

    # Automatically activate Git projects or other customized virtualenvwrapper projects based on the

    # directory name of the project. Virtual environment name can be overridden

    # by placing a .venv file in the project root with a virtualenv name in it.

    function workon_cwd {

      if [[ -z "$WORKON_CWD" ]]; then
        local WORKON_CWD=1

        # Check if this is a Git repo

        local GIT_REPO_ROOT=""
        local GIT_TOPLEVEL="$(git rev-parse --show-toplevel 2> /dev/null)"
        if [[ $? == 0 ]]; then
          GIT_REPO_ROOT="$GIT_TOPLEVEL"
        fi

        # Get absolute path, resolving symlinks

        local PROJECT_ROOT="${PWD:A}"
        while [[ "$PROJECT_ROOT" != "/" && ! -e "$PROJECT_ROOT/.venv" \
                 && ! -d "$PROJECT_ROOT/.git"  && "$PROJECT_ROOT" != "$GIT_REPO_ROOT" ]]; do

          PROJECT_ROOT="${PROJECT_ROOT:h}"

        done
        if [[ "$PROJECT_ROOT" == "/" ]]; then

          PROJECT_ROOT="."
        fi
        # Check for virtualenv name override
        if [[ -f "$PROJECT_ROOT/.venv" ]]; then

          ENV_NAME="$(cat "$PROJECT_ROOT/.venv")"

        elif [[ -f "$PROJECT_ROOT/.venv/bin/activate" ]];then
          ENV_NAME="$PROJECT_ROOT/.venv"
        elif [[ "$PROJECT_ROOT" != "." ]]; then

          ENV_NAME="${PROJECT_ROOT:t}"

        else
          ENV_NAME=""
        fi
        if [[ "$ENV_NAME" != "" ]]; then
          # Activate the environment only if it is not already active
          if [[ "$VIRTUAL_ENV" != "$WORKON_HOME/$ENV_NAME" ]]; then
            if [[ -e "$WORKON_HOME/$ENV_NAME/bin/activate" ]]; then
              workon "$ENV_NAME" && export CD_VIRTUAL_ENV="$ENV_NAME"
            elif [[ -e "$ENV_NAME/bin/activate" ]]; then
              source $ENV_NAME/bin/activate && export CD_VIRTUAL_ENV="$ENV_NAME"
            fi
          fi
        elif [[ -n $CD_VIRTUAL_ENV && -n $VIRTUAL_ENV ]]; then
          # We've just left the repo, deactivate the environment
          # Note: this only happens if the virtualenv was activated automatically
          deactivate && unset CD_VIRTUAL_ENV
        fi

      fi
    }
  
    # Append workon_cwd to the chpwd_functions array, so it will be called on cd
    # http://zsh.sourceforge.net/Doc/Release/Functions.html
    if ! (( $chpwd_functions[(I)workon_cwd] )); then
      chpwd_functions+=(workon_cwd)
    fi
  fi