Как в grab ввести какой-либо текст в форму, которая не имеет атрибута input?

g.doc.set_input('Post', 'your text here')

Traceback (most recent call last):
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\selection\base.py", line 81, in one
    return self.selector_list[0]
IndexError: list index out of range
 
During handling of the above exception, another exception occurred:
 
Traceback (most recent call last):
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\selection\base.py", line 92, in node
    return self.one().node()
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\selection\base.py", line 86, in one
    raise DataNotFound(m)
weblib.error.DataNotFound: Could not get first item for .//*[@name="Post"] query of class XpathSelector
 
During handling of the above exception, another exception occurred:
 
Traceback (most recent call last):
  File "C:\Users\Глеб\Desktop\Python\myprogram.py", line 13, in <module>
    g.doc.set_input('Post', '+++')
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\grab\document.py", line 479, in set_input
    self.choose_form_by_element('.//*[@name="%s"]' % name)
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\grab\document.py", line 711, in choose_form_by_element
    elem = self.select(xpath).node()
  File "C:\Users\Глеб\AppData\Local\Programs\Python\Python35\lib\site-packages\selection\base.py", line 97, in node
    raise DataNotFound(m)
weblib.error.DataNotFound: Could not get first item for .//*[@name="Post"] query of class XpathSelector