Add some comments.

1 files changed, 9 insertions, 0 deletions

diff --git a/coverage/bytecode.py b/coverage/bytecode.py
index ab522d6c..61c311eb 100644
--- a/coverage/bytecode.py
+++ b/coverage/bytecode.py
@@ -5,10 +5,19 @@ import opcode, sys, types
 class ByteCode(object):
     """A single bytecode."""
     def __init__(self):
+        # The offset of this bytecode in the code object.
         self.offset = -1
+
+        # The opcode, defined in the `opcode` module.
         self.op = -1
+
+        # The argument, a small integer, whose meaning depends on the opcode.
         self.arg = -1
+
+        # The offset in the code object of the next bytecode.
         self.next_offset = -1
+
+        # The offset to jump to.
         self.jump_to = -1