diff --git a/eth/rlp/headers.py b/eth/rlp/headers.py
index <HASH>..<HASH> 100644
--- a/eth/rlp/headers.py
+++ b/eth/rlp/headers.py
@@ -144,9 +144,7 @@ class BlockHeader(rlp.Serializable):
             nonce=nonce,
         )
 
-    #TODO implement long repr in Serializeable (or is it already there??)
-    # implement this short version, too:
-    def __repr__(self) -> str:
+    def __str__(self) -> str:
         return '<BlockHeader #{0} {1}>'.format(
             self.block_number,
             encode_hex(self.hash)[2:10],
Move shorter Header __repr__ string to __str__

Use new default repr that will come with the next release of RLP, but
keep the short version as __str__. This fits with the semi-standard of
short visually useful str, and a complete readout via repr.

Remove comment about RLP, proposed in:
<URL>