def _validate_entity_params(id, df, time_index):
    """Validation checks for Entity inputs"""
    assert isinstance(id, str), 'Entity id must be a string'
    assert len(df.columns) == len(set(df.columns)), 'Duplicate column names'
    for c in df.columns:
        if not isinstance(c, str):
            raise ValueError(
                'All column names must be strings (Column {} is not a string)'
                .format(c))
    if time_index is not None and time_index not in df.columns:
        raise LookupError('Time index not found in dataframe')
