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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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