def __str__(self):
res = "<STR_LIT>"<EOL>for chrom in self.blocksByChrom:<EOL><INDENT>for block in self.blocksByChrom[chrom]:<EOL><INDENT>res += (str(block) + "<STR_LIT:\n>")<EOL><DEDENT><DEDENT>return res<EOL>
@summary: produce a string representation of this IndexedWig object.
          We just show the details of the blocks, we don't show
          individual wig elements since these are often not in memory