chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/sympy/printing/tree.py

@@ -0,0 +1,175 @@
+def pprint_nodes(subtrees):
+    """
+    Prettyprints systems of nodes.
+
+    Examples
+    ========
+
+    >>> from sympy.printing.tree import pprint_nodes
+    >>> print(pprint_nodes(["a", "b1\\nb2", "c"]))
+    +-a
+    +-b1
+    | b2
+    +-c
+
+    """
+    def indent(s, type=1):
+        x = s.split("\n")
+        r = "+-%s\n" % x[0]
+        for a in x[1:]:
+            if a == "":
+                continue
+            if type == 1:
+                r += "| %s\n" % a
+            else:
+                r += "  %s\n" % a
+        return r
+    if not subtrees:
+        return ""
+    f = ""
+    for a in subtrees[:-1]:
+        f += indent(a)
+    f += indent(subtrees[-1], 2)
+    return f
+
+
+def print_node(node, assumptions=True):
+    """
+    Returns information about the "node".
+
+    This includes class name, string representation and assumptions.
+
+    Parameters
+    ==========
+
+    assumptions : bool, optional
+        See the ``assumptions`` keyword in ``tree``
+    """
+    s = "%s: %s\n" % (node.__class__.__name__, str(node))
+
+    if assumptions:
+        d = node._assumptions
+    else:
+        d = None
+
+    if d:
+        for a in sorted(d):
+            v = d[a]
+            if v is None:
+                continue
+            s += "%s: %s\n" % (a, v)
+
+    return s
+
+
+def tree(node, assumptions=True):
+    """
+    Returns a tree representation of "node" as a string.
+
+    It uses print_node() together with pprint_nodes() on node.args recursively.
+
+    Parameters
+    ==========
+
+    assumptions : bool, optional
+        The flag to decide whether to print out all the assumption data
+        (such as ``is_integer`, ``is_real``) associated with the
+        expression or not.
+
+        Enabling the flag makes the result verbose, and the printed
+        result may not be deterministic because of the randomness used
+        in backtracing the assumptions.
+
+    See Also
+    ========
+
+    print_tree
+
+    """
+    subtrees = []
+    for arg in node.args:
+        subtrees.append(tree(arg, assumptions=assumptions))
+    s = print_node(node, assumptions=assumptions) + pprint_nodes(subtrees)
+    return s
+
+
+def print_tree(node, assumptions=True):
+    """
+    Prints a tree representation of "node".
+
+    Parameters
+    ==========
+
+    assumptions : bool, optional
+        The flag to decide whether to print out all the assumption data
+        (such as ``is_integer`, ``is_real``) associated with the
+        expression or not.
+
+        Enabling the flag makes the result verbose, and the printed
+        result may not be deterministic because of the randomness used
+        in backtracing the assumptions.
+
+    Examples
+    ========
+
+    >>> from sympy.printing import print_tree
+    >>> from sympy import Symbol
+    >>> x = Symbol('x', odd=True)
+    >>> y = Symbol('y', even=True)
+
+    Printing with full assumptions information:
+
+    >>> print_tree(y**x)
+    Pow: y**x
+    +-Symbol: y
+    | algebraic: True
+    | commutative: True
+    | complex: True
+    | even: True
+    | extended_real: True
+    | finite: True
+    | hermitian: True
+    | imaginary: False
+    | infinite: False
+    | integer: True
+    | irrational: False
+    | noninteger: False
+    | odd: False
+    | rational: True
+    | real: True
+    | transcendental: False
+    +-Symbol: x
+      algebraic: True
+      commutative: True
+      complex: True
+      even: False
+      extended_nonzero: True
+      extended_real: True
+      finite: True
+      hermitian: True
+      imaginary: False
+      infinite: False
+      integer: True
+      irrational: False
+      noninteger: False
+      nonzero: True
+      odd: True
+      rational: True
+      real: True
+      transcendental: False
+      zero: False
+
+    Hiding the assumptions:
+
+    >>> print_tree(y**x, assumptions=False)
+    Pow: y**x
+    +-Symbol: y
+    +-Symbol: x
+
+    See Also
+    ========
+
+    tree
+
+    """
+    print(tree(node, assumptions=assumptions))