def create_label(support, taxon, auxiliary_info):
    """Create label for Newick tree.
    
    Parameters
    ----------
    float
      Support value specified by label, or None
    str
      Taxon specified by label, or None
    str
      Auxiliary information, on None
        
    Returns
    -------
    str
      Valid newick label.
    """
    label = ''
    if support is not None and taxon:
        label = str(support) + ':' + taxon
    elif support is not None:
        label = str(support)
    elif taxon:
        label = taxon
    if auxiliary_info:
        label += '|' + auxiliary_info
    return label
