HELP_MSG

#define HELP_MSG

Value:

  "Truncate an operator or a state.\n"                   \
  << "If the output is unspecified and a MPO is truncated, it will be added to the input lattice. " \
  << "If an MPS is truncated, it will overwrite the input file.\n" \
  << "Usage: " << argv[0] << " [options] <[-i] input state|lat:operator> [[-o] output state|operator name]\n" \
  << opt

Help message to be shifted into cout/cerr on error.