Consider using the platform’s DatasetBuilder class. Something like:
from java.lang import Integer, String
from com.inductiveautomation.ignition.common.util import DatasetBuilder
def someFunction():
b = DatasetBuilder.newBuilder().colNames("col1", "col2").colTypes(Integer, String)
for x in range(5):
b.addRow(x, "V%d" % x)
return b.build()