The available columns for any given table are fetched from a system table called "sys_tablecolumns". A specific table name is provided in the WHERE criteria to restrict the table from which the column information is fetched:

import cdata.graphql as mod
conn = mod.connect("AuthScheme=OAuth;OAuthVersion=2.0;CallbackURL=http://localhost:33333;OauthClientId=MyOAuthClientId;OAuthClientSecret=MyOAuthClientSecret;OAuthAccessTokenURL=https://mysite.com/login/oauth/access_token;")
cur = conn.cursor()
cmd = "SELECT * FROM sys_tablecolumns WHERE TableName = 'Users'"
cur.execute(cmd)
rs = cur.fetchall()
for row in rs:
	print(row)