def which(program):
exe = find_executable(program)<EOL>if exe is None:<EOL><INDENT>raise ValueError("<STR_LIT>" % program)<EOL><DEDENT>return exe<EOL>
Find full path of executable program

    Parameters
    ----------
    program : `str`
        path of executable name for which to search

    Returns
    -------
    programpath
        the full absolute path of the executable

    Raises
    ------
    ValueError
        if not executable program is found