def list_to_str ( lst ) : if len ( lst ) == 1 : str_ = lst [ 0 ] elif len ( lst ) == 2 : str_ = ' and ' . join ( lst ) elif len ( lst ) > 2 : str_ = ', ' . join ( lst [ : - 1 ] ) str_ += ', and {0}' . format ( lst [ - 1 ] ) else : raise ValueError ( 'List of length 0 provided.' ) return str_
how to return a string formed by concatenating all the elements in a list in python
Turn a list into a comma - and / or and - separated string .
def list_to_str(lst):
    """
    Turn a list into a comma- and/or and-separated string.

    Parameters
    ----------
    lst : :obj:`list`
        A list of strings to join into a single string.

    Returns
    -------
    str_ : :obj:`str`
        A string with commas and/or ands separating th elements from ``lst``.

    """
    if len(lst) == 1:
        str_ = lst[0]
    elif len(lst) == 2:
        str_ = ' and '.join(lst)
    elif len(lst) > 2:
        str_ = ', '.join(lst[:-1])
        str_ += ', and {0}'.format(lst[-1])
    else:
        raise ValueError('List of length 0 provided.')
    return str_