Fix write zero with sign

Author: Hong-Thai Nguyen

cfonb/tests/test_statement.py

@@ -34,6 +34,8 @@ def test_number_format(self):
         assert_equal(number_format(12340), '1234{')
         assert_equal(number_format(None), '')
         assert_equal(number_format(''), '')
+        assert_equal(number_format(0), '0{')
+        assert_equal(number_format(00), '0{')
 
     def test_parse_with_original_content(self):
         content = '''0115589    29701EUR2 01717651230  220620AAAA BB CCCCC KERHHHH                             0000000352431O0000            

cfonb/writer/statement.py

@@ -119,12 +119,15 @@ def _render_footer(self):
 
 
 def number_format(number):
-    if not number:
+    if number is None or not str(number):
         return ''
+    elif number == 0:
+        return '0{'
 
     _number = str(number).replace('.', '')
     _number = _number.replace('-', '')
     last_number = _number[-1]
     if number < 0:
         last_number = '-' + last_number
+
     return _number[0:len(_number) - 1] + LAST_LETTER_NUMBER.get(last_number)