1.1 --- a/allpy/base.py	Thu Dec 16 23:45:57 2010 +0300
     1.2 +++ b/allpy/base.py	Fri Dec 17 00:18:19 2010 +0300
     1.3 @@ -335,7 +335,7 @@
     1.4      """
     1.5      pass
     1.6  
     1.7 -class Block(object):
     1.8 +class Block(Alignment):
     1.9      """Block of alignment.
    1.10  
    1.11      Block is intersection of a set of columns & a set of rows. Most of blocks
    1.12 @@ -352,7 +352,8 @@
    1.13      columns = ()
    1.14      """List of columns in block."""
    1.15  
    1.16 -    def __init__(self, alignment, sequences=None, columns=None):
    1.17 +    @classmethod
    1.18 +    def from_alignment(cls, alignment, sequences=None, columns=None):
    1.19          """Build new block from alignment.
    1.20  
    1.21          If sequences are not given, the block uses all sequences in alignment.