fix: return a single node when possible in seq
fix: indentation in vm
fix: indentation in base test
fix: using symbol name to lookup environment in vm
fix: coding style of bin/r7rs
Revert "mod: using string instead of symbol to lookup in env"

This reverts commit 827fe371e5de5ad9a5f985fe6c10c17d025ee4b2.

Conflicts:
	src/vm.js
Revert "fix: using symbol name to lookup environment in vm"

This reverts commit e2a95cf244a891492e8b437c28ff2647c8d8a778.

Conflicts:
	src/vm.js
add: Syntax class into objects index
fix: export syntax class
fix: add environment lookup in pass1
fix: add type for syntax