user: Demonstrate the C code that generates the assembly output below:

```asm
<expand>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  movb   $0x0,-0xa(%rbp)
  movb   $0x0,-0x9(%rbp)
  movl   $0x0,-0x8(%rbp)
  movl   $0x0,-0x4(%rbp)
  jmp    L51
L4:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    $0x2d,%al
  jne    L99
  mov    -0x8(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L121
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  jne    L77
L121:
  mov    -0x8(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L2
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L2
L77:
  mov    -0x8(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %al,-0xa(%rbp)
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  mov    %al,-0x9(%rbp)
  movsbl -0xa(%rbp),%eax
  mov    %eax,%edi
  call   <tolower@plt>
  mov    %al,-0xa(%rbp)
  movsbl -0x9(%rbp),%eax
  mov    %eax,%edi
  call   <tolower@plt>
  mov    %al,-0x9(%rbp)
  mov    -0x4(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  cmp    %al,-0xa(%rbp)
  jne    L122
  movzbl -0xa(%rbp),%eax
  add    $0x1,%eax
  mov    %al,-0xa(%rbp)
  jmp    L122
L105:
  movzbl -0xa(%rbp),%edx
  mov    %edx,%eax
  add    $0x1,%eax
  mov    %al,-0xa(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0x1(%rax),%ecx
  mov    %ecx,-0x4(%rbp)
  movslq %eax,%rcx
  mov    -0x20(%rbp),%rax
  add    %rcx,%rax
  mov    %dl,(%rax)
L122:
  movzbl -0xa(%rbp),%eax
  cmp    -0x9(%rbp),%al
  jle    L105
  jmp    L99
L2:
  cmpl   $0x0,-0x8(%rbp)
  je     L25
  mov    -0x8(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L99
L25:
  mov    -0x4(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    %edx,-0x4(%rbp)
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movb   $0x2d,(%rax)
L99:
  addl   $0x1,-0x8(%rbp)
L51:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L4
  mov    -0x4(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  nop
  leave
  ret
```

assistant: ```c
void expand(char s1[], char s2[]) {
  int i, j;
  char start = 0;
  char end = 0;
  for (i = 0, j = 0; s1[i] != '\0'; i++) {
    if (s1[i] == '-') {
      if ((isalpha(s1[i - 1]) && isalpha(s1[i + 1])) || (isdigit(s1[i - 1]) && isdigit(s1[i + 1]))) {
        start = s1[i - 1];
        end = s1[i + 1];
        start = tolower(start);
        end = tolower(end);
        if (start == s2[j - 1]) {
          start++;
        }
        while (start <= end) {
          s2[j++] = start++;
        }
      } else {
        if (i == 0 || s1[i + 1] == '\0') {
          s2[j++] = '-';
        }
      }
    }
  }
  s2[j] = '\0';
}
```