Reads an encapsed string
function(expect, isBinary = false) {
    let node = this.node("encapsed");
    this.next();
    const start = this.lexer.yylloc.prev_offset - (isBinary ? 1 : 0);
    const value = [];
    let type = null;

    if (expect === "`") {
      type = this.ast.encapsed.TYPE_SHELL;
    } else if (expect === '"') {
      type = this.ast.encapsed.TYPE_STRING;
    } else {
      type = this.ast.encapsed.TYPE_HEREDOC;
    }

    // reading encapsed parts
    while (this.token !== expect && this.token !== this.EOF) {
      value.push(this.read_encapsed_string_item(true));
    }

    this.expect(expect) && this.next();
    node = node(
      value,
      this.lexer._input.substring(start - 1, this.lexer.yylloc.first_offset),
      type
    );

    if (expect === this.tok.T_END_HEREDOC) {
      node.label = this.lexer.heredoc_label;
    }
    return node;
  }