'Create a <textline/> XML element
Uses **kwargs:
*math_display*: If True, then includes a MathJax display of user input
*size*: An integer representing the width of the text line'

@staticmethod
def textline_input_xml(**kwargs):

    math_display = kwargs.get('math_display', False)
    size = kwargs.get('size', None)
    input_element_label = kwargs.get('input_element_label', '')
    input_element = etree.Element('textline')
    if input_element_label:
        input_element.set('label', input_element_label)
    if math_display:
        input_element.set('math', '1')
    if size:
        input_element.set('size', str(size))
    return input_element
