def get_largest_mol(mol_list):
    """
    Given a list of rdkit mol objects, returns mol object containing the
    largest num of atoms. If multiple containing largest num of atoms,
    picks the first one

    Args: 
        mol_list(list): a list of rdkit mol object.
    
    Returns:
        the largest mol.
    """
    num_atoms_list = [len(m.GetAtoms()) for m in mol_list]
    largest_mol_idx = num_atoms_list.index(max(num_atoms_list))
    return mol_list[largest_mol_idx]