#NEXUS
 BEGIN TAXA;
       DIMENSIONS ntax=4;
       TAXLABELS  A B C D;
 END;
 BEGIN CHARACTERS;
       DIMENSIONS ntax=4 nchar=25;
       FORMAT DATATYPE=protein;
 MATRIX
   A     IKKGANLFKTRCAQCHTVEKDGGNI
   B     LKKGEKLFTTRCAQCHTLKEGEGNL
   C     STKGAKLFETRCKQCHTVENGGGHV
   D     LTKGAKLFTTRCAQCHTLEGDGGNI
 ;
 END;
 BEGIN TREES;
       TREE my_tree = (((A:1,B:1):1,D:0.5):1,C:2)root;
 END;