Query: how to make conda default python environment

Relevant code:
def create_conda_env(sandbox_dir, env_name, dependencies, options=()):
    """
    Create a conda environment inside the current sandbox for the given list of dependencies and options.

    Parameters
    ----------
    sandbox_dir : str
    env_name : str
    dependencies : list
        List of conda specs
    options
        List of additional options to pass to conda.  Things like ["-c", "conda-forge"]

    Returns
    -------
    (env_dir, env_name)
    """

    env_dir = os.path.join(sandbox_dir, env_name)
    cmdline = ["conda", "create", "--yes", "--copy", "--quiet", "-p", env_dir] + list(options) + dependencies

    log.info("Creating conda environment: ")
    log.info("  command line: %s", cmdline)
    subprocess.check_call(cmdline, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
    log.debug("Environment created")

    return env_dir, env_name

Similar but not relevant code:
def update(packages, env=None, user=None):
    """
    Update conda packages in a conda env

    Attributes
    ----------
        packages: list of packages comma delimited
    """
    packages = ' '.join(packages.split(','))
    cmd = _create_conda_cmd('update', args=[packages, '--yes', '-q'], env=env, user=user)
    return _execcmd(cmd, user=user)

Similar but not relevant code:
def venv():
    """Install venv + deps."""
    try:
        import virtualenv  # NOQA
    except ImportError:
        sh("%s -m pip install virtualenv" % PYTHON)
    if not os.path.isdir("venv"):
        sh("%s -m virtualenv venv" % PYTHON)
    sh("venv\\Scripts\\pip install -r %s" % (REQUIREMENTS_TXT))

Similar but not relevant code:
def _find_conda():
    """Find the conda executable robustly across conda versions.

    Returns
    -------
    conda : str
        Path to the conda executable.

    Raises
    ------
    IOError
        If the executable cannot be found in either the CONDA_EXE environment
        variable or in the PATH.

    Notes
    -----
    In POSIX platforms in conda >= 4.4, conda can be set up as a bash function
    rather than an executable. (This is to enable the syntax
    ``conda activate env-name``.) In this case, the environment variable
    ``CONDA_EXE`` contains the path to the conda executable. In other cases,
    we use standard search for the appropriate name in the PATH.

    See https://github.com/airspeed-velocity/asv/issues/645 for more details.
    """
    if 'CONDA_EXE' in os.environ:
        conda = os.environ['CONDA_EXE']
    else:
        conda = util.which('conda')
    return conda

Similar but not relevant code:
def activate():
    """
    Usage:
      containment activate
    """
    # This is derived from the clone
    cli = CommandLineInterface()
    cli.ensure_config()
    cli.write_dockerfile()
    cli.build()
    cli.run()

Similar but not relevant code:
def init():
    """
    Execute init tasks for all components (virtualenv, pip).
    """
    print(yellow("# Setting up environment...\n", True))
    virtualenv.init()
    virtualenv.update_requirements()
    print(green("\n# DONE.", True))
    print(green("Type ") + green("activate", True) + green(" to enable your virtual environment."))